/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.trino.operator.scalar;

import io.trino.annotation.UsedByGeneratedCode;
import io.trino.spi.function.ScalarFunction;
import io.trino.spi.function.SqlType;
import io.trino.spi.type.StandardTypes;

import static java.util.Objects.checkFromToIndex;

public final class CombineHashFunction
{
    private CombineHashFunction() {}

    @ScalarFunction(value = "combine_hash", hidden = true)
    @SqlType(StandardTypes.BIGINT)
    public static long getHash(@SqlType(StandardTypes.BIGINT) long previousHashValue, @SqlType(StandardTypes.BIGINT) long value)
    {
        return (31 * previousHashValue + value);
    }

    @UsedByGeneratedCode
    public static void combineAllHashesWithConstant(long[] hashes, int fromIndex, int toIndex, long value)
    {
        checkFromToIndex(fromIndex, toIndex, hashes.length);

        for (int i = fromIndex; i < toIndex; i++) {
            hashes[i] = (31 * hashes[i]) + value;
        }
    }
}
